In various optical disk drives, such as CD-RW, DVD+R\RW, DVD−R\RW or DVD-RAM etc., a laser diode drive (LDD) provides a driving current to a laser diode (LD) for generating a laser power, thereby the laser diode can read or write the disk in the optical disk drive.
There are two types of power interfaces applied in the LDD for controlling the reading or writing powers of the laser diode, one type is a transistor-transistor logic (TTL) interface, another is a low voltage differential signaling (LVDS) interface. The TTL interface is often used in the situations requiring just a lower response rate, such as a stable reading power control in CD-RW or DVD-RW devices. The LVDS interface is often used in the situations requiring a higher response rate, such as a writing power control in DVD+R 16× speed, DVD-RAM 5× speed or DVD-RAM 16× speed devices etc.
FIG. 1 shows a conventional power control of DVD+/−R/RW in a single-pulse mode. When writing data in the DVD+/−R/RW disk, the signal pulse power control signal as shown in FIG. 1 is commonly adopted. In the single-pulse mode of DVD+/−R/RW, a cooling pulse is always generated for forming a perfect pit. However, the common LDD uses the TTL interface to implement reading power control no matter in reading or writing data. As shown in the FIG. 1, the TTL will be also set to generate a cooling pulse. Due to the slow response rate, the cooling pulse is not as sharp as required. Therefore, the cooling pulse can not be precisely controlled. Alternatively, if the LDD use the LVDS to implement the read power control for reading or writing data, the radio frequency (RF) signal read from the disk may be easily induced noises due to the higher response rate of the LVDS interface The noises accompanied with the RF signal will increase a variation of signal to noise ratio (S/N ratio) during data transmission in the optical disk drive. The S/N ratio variation will degrade the recording performance of the optical disk drive.
Furthermore, the present DVD drive is required to support at least three DVD formats, i.e. DVD+R/RW, DVD−R/RW and DVD-RAM. The different write strategies are applied for writing different disk types or writing the same disk under different writing speeds in order to obtain an optimal writing performance. The conventional power control systems or methods cannot provide a flexible LDD setting for complying with different write strategies. Therefore, a novel flexible power control system and method are provided to resolve the above problems.